Aircraft structural stringers are well-known for having an ideal lightweight, high performance structural supporting capability. In cross section they have a central inwardly channel-shaped portion which on its channel legs has transversely extending flanges at right angles thereto, the flanges having returning ends which form two outwardly directed channels substantially more shallow than the central inwardly opening channel. The stringers are secured to the aircraft structure through the base of the outwardly opening channel by means of rivets or other attaching devices.
It is necessary to secure various types of supports to the stringers for supporting cables and other materials, but drilling through the flanges causes stress problems. Thus, attaching supports through openings in the flanges is not an acceptable practice.
In the prior art, ratchet-type mounting plates have been used for securing support attachments to stringers. These plates have been made with one end adapted to fit over and on the end of a stringer flange and have employed a ratchet-secured strap to fit over the other stringer flange to secure the plate.
Problems with this type of plate are that stress load distribution on the stringer cause twisting thereof and the location of the cable support, for example, is impossible to determine exactly. These problems have made the aforesaid type mounting plates unsatisfactory.
In the prior art other types of stringer attachments used include both metal and plastic mounting plates held in place by being screwed on spring clips. These types of structures have been overly complex and costly.